First post, by Spirantho
Hi,
I noticed this morning a thread (which I now can't find) about switching a 386SX CPU, so I thought I'd share my knowledge and maybe save other people the hassle I've been through.
Some points:
The 386SX chips are all - more or less - the same, be they Intel or AMD or whatever.
The 486SLC chips are different. There are two cores:
The Cyrix core is different to the IBM core, which is faster.
The Cyrix chips have 1KB cache, the IBM has 8KB, at least on the faster chips.
Be careful! If the code on the chip has a "V" in it, it's a 3.3V part! To switch with an SX, you need 5V. So:
Cx486SLC/e-25 = good! This is a direct replacement for a 386SX!
Tx486SLC/c-25 = good!
Cx486SLC/e-V25 = bad! This is a 3.3V part
Tx486SLC/e-V25 = bad!
Now, if you want real speed, you need a clock-doubled part. You can find these on clip-on accelerators, but they can be a bit unreliable.
Essentially, you need to see if the clip-on chip has a daughterboard with a voltage converter on it. If it does, it's no good.
Cx486SLC2-50MP = good! 50MHz power! This is the fastest I've found yet.
Tx486SLC2 = beware! I believe these are 3.3V parts!
IBM 486SLC/2 and above = all (doubled?) IBM parts are 3.3V! These are not direct replacements.
In other words:
Tx486SLC/e-xx, Cx486SLC/e-xx and Cx486SLC2-xxMP are all good, with the latter being the fastest.
There may be others, but if you want to upgrade your 386SX chip (for instance, on a bridgeboard) then these are the chips to go for!
Hope that helps some other crazy people like me for whom a clip-on chip just isn't good enough (or in my case, because the clip got old and became unreliable!)
--
Ian Gledhill
http://www.mutant-caterpillar.co.uk/shop/ for all your 8-bit and 16-bit needs!